JP2012509762A - Apparatus and method for depositing a powder mixture for forming an object having a composition gradient - Google Patents

Abstract

The present invention is generally an apparatus (1) for depositing a powder mixture to form an object having a composition gradient for accommodating each of different powders (A1,..., An). A plurality of tanks (R1,..., Rn), a powder mixer (30) including a mixing member (32) disposed below the tank and rotatably attached thereto, and the tank cooperate with each other. A plurality of powder distribution means (4, 6), each designed to adjust the mass flow rate of the powder discharged toward the head, a powder mixture collector (56) arranged under the mixer, And a powder mixture dispenser (60) disposed below.
[Selection] Figure 1

Description

  The present invention relates generally to the field of objects having compositional gradients, also known as FGM ("functionally graded material").

  This type of object is applied in a very large number of technical fields. As an example, this can be an object composed of a ceramic material and a metal material, and the proportion of mass, also referred to as the mass ratio of both of these materials in the mixture, varies over time in the same object, Set according to the occasional needs. For example, an object can be designed to gradually change in its given direction from a completely ceramic material composition to a completely metallic material composition, passing through a transition mixing region between both materials. it can. This is referred to as the composition gradient of this object in this given direction.

  To make this type of object, a technique of depositing powder is used, followed by consolidation of the deposit by known techniques such as sintering or hot isostatic pressing.

  Therefore, the apparatus used to make an object with this type of composition gradient comprises an apparatus for depositing a powder mixture, which is movable, for example by a robot, with respect to a support intended to deposit the mixture. .

  However, with known deposition equipment designs, it is not possible to perfect and satisfactorily homogenize the resulting powder mixture, which is consistent between the fabricated object and the desired object. It means that lack can occur. Of course, this drawback also appears as a problem of the reproducibility of the desired object.

In order to find a remedy for these drawbacks, first, the object of the present invention is an apparatus for depositing a powder mixture to form an object having a composition gradient,
A plurality of tanks (R1,..., Rn) for accommodating each of the different powders (A1,..., An);
A powder mixer disposed below the tank (R1,..., Rn), including a rotatably mounted mixing member, for causing the powder (A1,..., An) from the tank to collide When,
A plurality of powder distribution means, each of which cooperates with the tanks (R1,..., Rn), each designed to adjust the mass flow rate of the powder discharged from the tank toward the mixer;
A powder mixture collector disposed below the mixer and in communication with the mixer;
A powder mixture dispenser disposed below the powder mixture collector and in communication with the powder mixture collector;
It is an apparatus provided with.

  The device according to the invention is simple enough to make the powder mixture exiting the dispenser sufficiently uniform, to suppress the lack of consistency between the created object and the desired object, or even to eliminate it completely. It is advantageous to have a simple design. Thus, this deposition apparatus enables reliable, controlled and reproducible production of the object and ensures a specific composition at each point of the formed object.

  The number of tanks “n” is selected depending on the number of different powders desired to produce the same object. Therefore, this is by no means limited to two. Furthermore, regardless of the number of tanks incorporated in the apparatus, the tank may of course already contain a powder corresponding to a mixture of a plurality of given powders.

  Preferably, the rotatably mounted mixing member has a generally conical first powder impingement surface having an axis corresponding to the rotational axis of the member.

  Preferably, the mixer includes a generally conical second powder impingement surface, the second powder impingement surface being generally conical for passing powder between the first powder impingement surface. In order to form a gap of the shape, the first powder impingement surface is disposed coaxially and oppositely.

  Preferably, the generally conical first powder impingement surface has one or more recesses. These recesses further improve powder mixing.

  Preferably, the mixing member is rotatably mounted on a guide part of the mixer, and the guide part is provided with one or more passage orifices in communication therewith above the powder mixture collector.

  Preferably, in order to obtain an efficient flow due to the gravity of the powder mixture through the guide part, at any point of the defining surface that defines each of the passage orifices, it is less than 40 ° perpendicular to this defining surface, preferably Forms an angle of less than 30 °.

  For the same purpose, it is preferred that at any point of the defining surface of the powder mixture collector, this defining surface forms an angle with the vertical line of less than 40 °, preferably less than 30 °.

  Optionally, the apparatus further comprises a collector of powder (A1,..., An) disposed below the distribution means and between it and the mixer. In this regard, for the same purpose of obtaining an efficient flow of the powder by gravity within the collector, this defining surface is at any point of the defining surface of the powder collector (A1,..., An). It is preferred to form an angle with the vertical line of less than 40 °, preferably less than 30 °.

  Preferably, each of the distribution means takes the form of a powder delivery device by vibration of the powder support element. Therefore, it is possible to completely control the mass flow rate of the powder discharged from each distribution means in accordance with the vibration frequency and amplitude of the delivery means. As a result of this, the composition of the resulting object is also under perfect control.

  An object of the present invention is an installation for depositing a powder mixture for forming an object having a composition gradient, comprising a deposition apparatus as described above attached to a spatial movement means, and said movement means and said distribution It is also a facility with a control unit that can control each of the means.

Preferably, the control unit controls each of the distribution means over a period T,
Change over time of the mass ratio of the powders A1,..., An in the powder mixture to be deposited over the period T;
A representative value of the specific gravity of the powder mixture after deposition according to the mass ratio of the powders A1, ..., An in the mixture;
Associated with a deposition apparatus, which corresponds to the time elapsed between the moment when control is transmitted to the powder distribution means to obtain a powder mixture having a given mass ratio and the moment when this powder mixture is deposited Waiting time (tl),
Consider.

  Preferably, the period T corresponds to the duration of forming the entire powder mixture layer, or even the duration of forming a plurality of layers superimposed.

  The change over time of the mass ratio of the powders A1,..., An in the powder mixture to be deposited over a period T is predetermined according to the desired composition at each point of the object to be produced. This change over time can take the form of a continuous curve over time, having a given instantaneous value, or any other form.

  Preferably, the mass of each powder for each time t of period T, in order to ensure that the deposited powder mixture layer has a substantially constant thickness, especially for the purpose of overlaying multiple layers. The flow rate is actually determined from the desired mass ratio of the mixture at this time t and a representative value of the specific gravity of the mixture after deposition. In this regard, it should be noted that these representative values can be predetermined, for example by calibration. This can be the actual specific gravity, density, or any other value that is estimated to represent it.

  Further, as can be seen from the above, in order to take into account the passage time of the powder in the apparatus, the determination of the mass flow rate to be applied at each time t in the period T is performed taking the above-described waiting time into consideration. The waiting time, in other words, corresponds to the delay that occurs in the powder from the dispensing instruction associated with the powder until the powder actually deposits on the support after it exits the dispenser.

  Next, the mass flow rate of the powder determined by the above-mentioned method is converted into control of the distribution means of these powders, and these controls take the form of electric signals supplied to these means, for example, The link to the control is also predetermined, for example by calibration.

  Preferably, the control unit takes into account changes over time of the position (x, y) to be employed in the powder mixture dispenser over the period T in order to control the deposition apparatus starting means over the period T.

  The position coordinates x and y can correspond to a planar reference system associated with the support on which the powder mixture layer is to be deposited. If it is intended to produce the object by layer superposition, the coordinates can further include a variable z relating to the height of the dispenser relative to the support on which the layer is deposited.

  As a matter of course, it is certain that the control of the device starting means and the control of the distributing means are fixed in time with respect to each other.

  An object of the present invention is a method for producing an object having a composition gradient by the above-described apparatus or equipment, wherein at least one deposited on the support by moving the powder mixing dispenser relative to the support. It is also a method for producing an object having a composition gradient from the formation of two powder mixture layers.

  Preferably, to produce the powder mixture layer, the powder mixture dispenser is moved to sweep the surface of the support on which the layer is to be deposited, during which control of at least one of the dispensing means To change. This allows one or more compositional gradients to be advantageously obtained in the plane of the thickness of the deposited layer, so that these gradients are added to those that can be obtained by superposition of multiple layers with different compositions. be able to.

  Other advantages and features of the invention will become apparent from the following non-limiting detailed description.

  This description is made with reference to the accompanying drawings.

FIG. 2 shows a cross-sectional view of an apparatus for depositing a powder mixture according to a preferred embodiment of the present invention. FIG. 2 shows a perspective view of a portion of the apparatus shown in FIG. The perspective view of the mixing member which belongs to the apparatus shown in FIG.1 and FIG.2 is shown. FIG. 3 shows a perspective view of a guide component of a powder mixer belonging to the apparatus shown in FIGS. 1 and 2. FIG. 3 shows a perspective view of a powder mixture collector belonging to the apparatus shown in FIGS. 1 and 2. The perspective view of the powder support body which is an integral part of the apparatus shown in FIG.1 and FIG.2, and belongs to the apparatus which sends out powder by vibration is shown. It is the schematic which shows operation | movement of the powder delivery apparatus by vibration. FIG. 6 shows a partial perspective view of a facility for depositing a powder mixture incorporating the deposition apparatus shown in FIGS. The operation | movement of the control unit with which the installation of FIG. 6 is provided is shown schematically. Fig. 4 schematically illustrates a sweep performed by a dispenser to produce a powder mixture layer performed during application of a method for producing an object having a composition gradient according to a preferred embodiment of the present invention. FIG. 9 is similar to FIG. 8 and shows a sweep according to an alternative embodiment. 1 schematically illustrates a method according to a preferred embodiment of the present invention in which a desired object having a composition gradient is made from a stack of a plurality of powder mixture layers. It is similar to FIG. 9 and shows an alternative embodiment. 1 is a cross-sectional view of an object having a composition gradient obtainable by the present invention. 1 is a cross-sectional view of an object having a composition gradient obtainable by the present invention. 1 is a cross-sectional view of an object having a composition gradient obtainable by the present invention.

  Referring to FIGS. 1 and 2, there is shown an apparatus 1 for depositing a powder mixture according to a preferred embodiment of the present invention. This apparatus 1, sometimes referred to as a deposition head, has a series of elements that are continuously positioned in a vertical direction corresponding to the direction of the axis 2 of the apparatus, and the axis 2 is used during the production of the object. It is preferably provided so as to be substantially perpendicular to the support intended for the deposition of the body mixture. This makes it possible in particular to ensure that the powder essentially passes through the device 1 by gravity before being discharged from the device 1, as will be described in detail below.

  A plurality of powder tanks are arranged in the upper part of the head 1. More specifically, in the preferred embodiment shown, two separate tanks are provided, ie tanks R 1 and R 2 are arranged around axis 2. As an indication, it should be noted that the tank is preferably positioned eccentric with respect to this axis which forms the center of symmetry of the entire tank, as viewed from above, ie along the direction of the axis 2.

  Tank R1 is filled with powder A1, and tank R2 is filled with powder A2 having a composition different from that of A1.

As an index example, the powder A1 is a metal material of the type known for example as Inconel 600 sold by Special Metals, which is nickel, chromium containing small amounts of carbon, silicon and magnesium. , And an iron composite alloy having both high corrosion resistance and excellent mechanical properties. The particle size can be about 50 μm to 120 μm. Also by way of example, the powder A2 is a ceramic material of, for example, zirconium oxide ZrO ₂ type, optionally premixed with yttrium trioxide Y ₂ O ₃ . The particle size can be about 1 μm to 120 μm.

  Therefore, in the illustrated embodiment, only two tanks containing different materials are provided in the deposition apparatus. However, depending on the desired object, it is possible to increase the number of different powders required to obtain this object to more than two, for example three, four or even more. In such a case, the deposition apparatus according to the invention is configured to incorporate the required number of tanks, preferably also distributed around the axis 2. Also, the control of this apparatus, which will be described in detail later, is naturally adapted according to the number of different powders to be applied.

  Each tank preferably has an upper opening for filling the apparatus with powder and an outlet orifice positioned on the opposite side of the opening along the vertical direction. Furthermore, at any point on the defining surface of each tank, this defining surface forms an angle with the vertical, preferably less than 40 °, and even more preferentially less than 30 ° relative to this direction. Thereby, the powder can flow appropriately from the top to the bottom of the tank toward the exit orifice only by gravity.

  Each tank R1, R2 is provided with a powder distribution means disposed below the associated tank and cooperating with the outlet orifice of that tank.

  In the preferred embodiment shown, each dispensing means takes the form of a powder delivery device by vibration of a powder support element, this type of delivery device being known per se, for example by reference herein. Is the type described in French Patent No. 2666077, which is incorporated by reference.

  Accordingly, the delivery device 4 is coupled to the tank R1, and the delivery device 6 is coupled to the tank R2. In general, each device 4, 6 has a vibration generator 8 that drives a rod 10 to reciprocate along an axis 12 of this rod, the axis 12 being along a horizontal line as shown in FIG. Is inclined by an angle α. The angle α can be about 20 ° to 40 °.

  The opposite end of the rod 10 is fixedly supported on a powder support 14, also referred to as a distribution plate, and the powder support element 14 is preferably arranged horizontally or slightly inclined with respect to the horizontal line. Accordingly, when the vibration generator 8 is energized, the support 14 performs a high-speed reciprocating motion in a direction corresponding to the direction of the axis 12 according to a given amplitude and frequency according to a control signal applied to the vibration generator 8. .

  FIG. 5 shows a part of the operation of the sending device 6 in order to explain it. As can be seen in FIG. 4, the powder support 14 comprises an attachment portion 16 for connection to the rod 10 and an opposite portion 18 for cutting out the powder. The opposite portion 18 forms a powder receptacle having a notch 20 for discharging powder, as shown in FIG. 5, and the outlet orifice 22 of the tank R2 faces the bottom of the receptacle 18 and is slightly away therefrom. Position away from. The clearance between the outlet orifice 22 and the bottom of the receptacle 18 can be adjusted according to the needs of the moment, and can be set to about 1 mm to 2 mm, for example.

  When the support 14 vibrates as schematically represented by a double arrow 24 oriented along the direction of reciprocation it receives, the powder A2 exiting the orifice 22 and contained in the bottom of the receptacle 18 is directed toward the notch 20. And then gradually fall toward the powder collector 26 described later by gravity.

  The mass flow rate of the powder A2 discharged through the notch 20 and falling onto the collector 26 only by gravity can be adjusted very accurately according to the amplitude and frequency of the vibration of the support 14. In this regard, between the control of, for example, an electrical signal applied to the delivery device 6 and the mass flow rate of the powder A2 discharged from the support 20 that can match the flow rate discharged from the tank R2, in advance. A correlation is established. This correlation, for example in the form of a value correspondence table, is preferably obtained by a calibration operation performed on the apparatus 1 prior to producing an object using the apparatus 1. Therefore, such a correlation is established for each powder intended for use. Further, even if only the operation of the device 6 is described, it should be understood that the operation of the device 4 is the same or similar because the device 4 is of the same design.

  Due to their enormous size, the vibration delivery devices 4, 6 extend substantially radially outward with respect to the axis 2 from their support 14.

  Thus, referring again to FIG. 1 in conjunction with FIG. 2, the deposition head 1 has a powder collector 26 under both supports 14, so that the powders A1 and A2 discharged from the respective notches are It falls into this collector by gravity.

  The powder collector 26 takes the form of a converging tube having a substantially conical defining surface 28 having an axis 2. Again, at any point of the defining surface 28, this surface is preferably less than 40 °, and even more preferentially, at any point of the defining surface 28 to facilitate the flow of the powders A1, A2 due to gravity within the converging tube 26. Makes an angle of less than 30 ° with respect to this direction.

  The collector 26 is opened downward so as to communicate with the powder mixer 30, and the powder mixer 30 includes a mixing member 32 attached so as to be rotatable along the axis 2 around the axis 2. The mixing member 32 has a rod 34 that penetrates the collector 26 toward the upper portion of the head 1, and the upper end of this rod has a means 36 for starting rotation about the axis 2, for example, a motor comprising a transmission belt. Combine with.

  The lower end of the rod 34 is connected to a larger portion of the mixing member 32 that forms the first powder impingement surface 40, which is generally conical with the axis 2 and extends downward. In addition, the mixer 30 also includes an outer fixed portion that surrounds the rotating mixing member 32. This fixed part has a second powder impingement surface 42 which is generally conical with an axis 2 and extends downwards and is arranged facing the first impingement surface 40. This also forms a generally conical gap 44 for the passage of powder.

  As shown in FIG. 3, the powder impingement surface 40 has one or more recesses 46, which preferably extend along a conical surface generatrix, for example, in a vertical plane passing through the axis 2. Note that even if only one recess 46 is visible in FIG. 3, due to the dynamic behavior of the rotating member 32, a plurality of recesses are preferentially distributed equidistantly around the axis 2 over 360 °. I want to be.

  A substantially conical gap 44 formed between both powder impingement surfaces 40, 42 is arranged so that the powder can impinge on the surface 40 and / or surface 42 of the member 32 multiple times. Therefore, it is advantageous that the thickness of the gap considered along the direction orthogonal to the axis of the cone corresponding to the axis 2 is 1 mm to 1 cm. Note that the thickness of the gap 44 varies due to the presence of the recess 46, and this thickness varies from 3 mm to 7 mm.

  Therefore, the powders A1 and A2 that fall by gravity in the annular space formed by the outlet orifice of the collector 26 and the rod 34 passing through the orifice are guided to the gap 44, and the cone having the recess 46 in the gap. Mix well as soon as it first strikes the surface 40. In this regard, the rotational speed of the unit 32 is set to a value that allows, for example, the same powder particles to collide with the rotating surface 40 about 10 times during residence in the mixer, and the rotational speed representing this is For example, about 3,000 rpm applied by means 36. Advantageously, during operation, the rotating member 32 is rotated in a direction opposite to the direction in which the recesses 46 are oriented to avoid material accumulation in these recesses 36. Therefore, in the example shown in FIG. 3, the rotating member 32 is rotated in the counterclockwise direction indicated by the arrow 47. Therefore, the rotation direction of the member 32 is preferentially determined by the nature and direction of the recess.

  In order to guide the rotation of the member 32, for example, a rolling bearing 50 is provided in the upper part of the rod 34 and another rolling bearing 50 is arranged between the lower end of the member 32 and a guide part 52 in the form of a plate. Located horizontally below the generally conical gap 44 that extends outwardly, this part 52 is provided with one or more passage orifices 54 above and in communication with the powder mixer collector 56.

  Each orifice 54 intended to allow the powder mixture to pass under the influence of gravity is less than 40 ° with respect to the vertical at any point of its defining surface, and even more preferentially with this direction less than 30 °. Again, the purpose is to promote proper flow of powder in the deposition head 1. These orifices 54 distributed around the axis 2 have a generally converging shape, which is best shown in FIG. 3 a showing an exemplary embodiment of the guide plate 52. In this FIG. 3 a, the part 52 about the axis 2 generally comprises a hub 53 having a central housing 55 for receiving rolling bearings, the inclined outer surface 57 of the hub 53 forming the radial inner surface of the orifice 54. I understand that An outer ferrule 59 is disposed concentrically with the hub 53, and its inclined inner surface 61 forms a radially outer surface of the orifice 54. On the other hand, radial arms 63 connect the hub 53 to the outer ferrule 59. Each arm 63 defines two orifices 54 on either side with an inclined surface that also satisfies the above definition for the angle to the vertical. The upper part of each radial arm 63 is preferably in the shape of as thin an edge as possible, thereby reducing the risk of powder accumulation on these edges.

  Referring again to FIG. 2, it can be seen that the powder mixture collector 56 located below the part 52 has a generally converged shape, similar to the orifice 54 through the part 52. Again, at any point on the defining surface 58 of the collector 56, this surface makes an angle with the vertical line of less than 40 °, and even more preferentially less than 30 °. The collector 56 centering on the axis 2 has an upper portion forming a seat portion 56 on which the outer ferrule of the guide component 52 is placed. The collector 56 has suitable dimensions to allow the powder mixture leaking from each of the orifices 54 provided in the part 52 to be collected. As shown in FIG. 3 b, means 67 can further be provided in the form of two stainless steel plates that intersect each other at 90 °, and by this means 67 inserted in the collector 56, the powder at the outlet of the orifice 54 The vortex effect exhibited by the mixture can be eliminated.

  Below the extension of the collector 56 is mounted a powder mixture dispenser 60, through which the mixture is again simply removed by gravity. This dispenser has a form of a linear flow path having a small diameter around the axis 2, for example, 2 mm to 5 mm.

  Note that the device is intended to be assembled from metal elements, such as stainless steel elements 316.

  Therefore, as apparent from the above, the powders A1 and A2 are composed of the tanks R1 and R2, the support 14 and 14 of the vibration delivery device, the collector 26, the orifice 54 for passing the guide component 52, the collector 56, and After continuously passing through the dispenser 60, it is discharged from the head 1 to form a powder mixture layer. Therefore, the expression “powder mixture” should be interpreted broadly. That is, this expression should refer to both the composition consisting of the powders A1 and A2 exiting the deposition head 1 and the composition consisting only of the powder A1 exiting from the head 1 or only the powder A2. Please keep in mind.

  Finally, it is suggested that each surface of the apparatus 1 that can come into contact with the powder is given a low roughness of, for example, an average surface roughness Ra of about 0.4 μm.

  Referring now to FIG. 6, an installation 100 for depositing a powder mixture incorporating the deposition head 1 described above can be seen. The head 1 is preferably attached to a spatial starter 102 of the robot type. The robot 102 is preferably designed to move the head at any point in a direct orthonormal reference system x, y, z, where the coordinate z of the reference coordinate system is the height of the head 1. This corresponds to the direction of the thickness, and thus the direction parallel to the axis 2.

  The equipment 100 includes a control unit 104. According to the control unit 104, the robot 102 can be controlled by the output S′1, and the cutting means 4 related to the powder A1 is controlled by the output S1. And the supply means 6 associated with the powder A2 can be controlled by the output S2. Further, the control unit 104 includes a computer type, a converter type, and other conventional elements, and can handle the control of the means 36 for starting the rotation of the mixing member 32 even if not shown.

  FIG. 7 shows a schematic diagram of an exemplary control unit 104. The first part is dedicated to generating control of the powder distribution means, and the second part is dedicated to controlling the robot 102.

  For the first part, unit 104 receives several pieces of information through inputs E1, E2, E3. The input E1 relates to the change over time of the mass ratio of the powders A1, A2 in the powder mixture to be deposited, which change over time is determined over a period T, which is then determined by the powder mixture. It is considered as a period that allows the entire layer to be deposited. Of course, this change in the mass ratio of the mixture over time is determined according to the desired composition of the layer to be deposited, the desired composition being variable at any point of the layer to be deposited or in certain cases. Is constant.

  The input E2 relates to a representative value of the specific gravity of the mixture according to the mass ratio of the powders A1 and A2 in the powder mixture after deposition. These representative values can preferably be determined in advance by calibration performed on this same equipment. This can be the actual specific gravity or density.

  The input E3 is from the moment when control is transmitted to the powder distribution means 4, 6 to obtain a powder mixture having a given mass ratio, until the moment when this powder mixture is deposited after leaving the dispenser 60. This corresponds to the waiting time (tl) associated with the deposition apparatus 1 corresponding to the elapsed time. This waiting time can also be determined by calibration performed on this same equipment.

  The unit 104 starts by first determining the change over time of the mass flow rate of the powders A1, A2 to be employed over the period T. In general, at every time t of period T, input E1 allows the setting of the ratio between both flow rates, and input E2 sets the respective values of these two flow rates while observing the commanded ratio. The input E3 allows the flow rate command to be advanced in time, so that a delay exists between the time the flow rate command is issued and the time the powder is deposited after extraction from the dispenser 60. Can be compensated.

  By considering the input E2, it is possible to set the flow rate to a value that ensures the formation of a layer having a substantially constant thickness, irrespective of changes over time in the composition of the powder mixture in this layer. Please note that. This has been found to be particularly advantageous when the desired object requires multiple layer superpositions, in which case any given layer is directly above the stack. (Direct uppermost) means that it should have a substantially planar and horizontal top surface to properly support the layer.

  Next, from the required change over time of the flow rate over the period T, the unit 104 generates the control of the first means 4 for supplying the powder A1 at the output S1, and also supplies the powder A2 at the output S2. The control of the second means 6 is generated. Therefore, the above-described correlation established in advance between the control applied to the delivery devices 4 and 6 and the mass flow rates of the powders A1 and A2 discharged from the support 20 is preferentially used.

  The second part of the unit 104, dedicated to the control of the robot 102, receives from the input E'1 information on the change over time over the period T at the position (x, y) to be adopted by the dispenser 60 of the head 1. receive. These pieces of information are predetermined and can change over time, preferably over the path that the dispenser 60 should follow to obtain a powder mixture layer, and preferably over the period T that should cover this path. Is generally expressed as a speed that is preferentially constant. The unit 104 ensures its movement in the xy plane by generating control of the starting means of the deposition head 1 in S′1 from E′1.

  In order to obtain the desired layer, it is of course certain that the control of the device starting means and the control of the dispensing means are fixed in time with each other.

  Referring now to FIG. 8, it can be seen that the reference coordinate system x, y, z can be associated with a substrate, i.e., substrate 108, on which a layer is to be deposited. An exemplary path 110 of the dispenser 60 is shown in the specific case of being a generally disc shaped layer. This path corresponds to a sweep intended to follow the layer at the surface of the support 108, for example in the form of a plurality of reciprocating strokes along the direction x, which moves along the direction y between each stroke. To do. During this movement, the composition of the powder mixture can of course be changed over time, especially for the purpose of forming one or more gradient compositions in the xy plane of the resulting layer. An alternative embodiment is shown in FIG. 8a, where the path 110a is spiral.

  Finally, it should be noted that this method can be extended to the formation of objects by stacking multiple layers 114 along direction z, as shown in FIG. In this case, the controls S1, S2, and S'1 can be provided over a period T corresponding to the duration required to make all of these layers. This is particularly true because the control S′1 preferably keeps the height of the dispenser 60 relative to the surface of the support 108 so that the distance between the lower end of the dispenser 60 and the pre-deposited layer is always substantially the same. It means that z is also manipulated.

  In FIG. 9, it can be seen that the support 108 is an integral part of the container 120 and forms the bottom thereof. Various layers 114 are sequentially deposited in the container 120 to form a desired stack that may have one or more compositional gradients along the z-axis.

  An alternative embodiment comprises the bottom 108 movable along the z-axis and the dispenser 60 fixed in this same direction, as schematically illustrated in FIG. 9a. In this situation, the bottom 108 takes the form of a piston that moves downward after the creation of each layer, preferably along a distance close to or equal to the layer thickness.

  As an indication, it should be noted that each layer 114 may have a thickness of about 0.25 mm and the final laminate may have a thickness of about 27 mm.

  Furthermore, once the powder mixture has been deposited, the compaction can proceed according to any known technique to obtain an object with a composition gradient. In the example shown in FIG. 9, the laminate is subsequently cold-compressed to make the assembly operable, i.e., to eliminate the risk of disturbing the laminate powder. The manufacturing process then continues by densifying the assembly with a hot isotropic compression operation, also referred to as HTC, although other techniques can be used without departing from the scope of the present invention. In order to perform this hot isostatic compression, the compressed laminate is first degassed and the laminate is sealed with a container 120 containing the laminate. Next, to obtain hot isostatic compression, the assembly is placed in a closed vessel at a temperature of about 1,325 ° C. and a pressure of about 1,400 bar to obtain a densification.

  As described above, the resulting three-dimensional object may have one or more composition gradients in any direction of the reference coordinate system x, y, z. In this regard, FIGS. 10a to 10c show objects that can be obtained with the present invention as cross-sectional views along the xz plane.

  In these figures, the darker the color, the greater the mass ratio of the powder A1 in the mixture, and the lighter the color, the greater the mass ratio of the powder A2 in the mixture. Thus, while FIGS. 10a and 10b show embodiments with gradually different composition gradients in the xz plane, the white dots in FIG. 10c are due to spheres embedded in a black envelope made of a different material. It can be equivalent.

  A plurality of uses can be considered for the object having the composition gradient thus produced. Such applications include aircraft jet engines, particularly reactor heat exchangers, steam reformers, biomass reactors, fuel cells, electrolyzers and the like.

  Of course, those skilled in the art of the present invention described above can make various modifications, merely as a non-limiting example.

Claims (15)

An apparatus (1) for depositing a powder mixture to form an object having a composition gradient,
A plurality of tanks (R1,..., Rn) for accommodating each of the different powders (A1,..., An);
A powder mixer (30) disposed below the tank (R1,..., Rn), including a mixing member (32) mounted rotatably, the powder (A1,..., An) from the tank A powder mixer (30) for colliding
A plurality of powder distribution means (4) each designed to adjust the mass flow rate of the powder discharged from the tank toward the mixer in cooperation with the tanks (R1,..., Rn). , 6) and
A powder mixture collector (56) disposed below and in communication with the mixer (30);
A powder mixture dispenser (60) disposed below the powder mixture collector (56) and in communication with the powder mixture collector;
A device comprising:   2. A device according to claim 1, wherein the rotatably mounted mixing member (32) has a generally conical first powder impingement surface (40) having an axis (2) corresponding to the axis of rotation of the member. A device characterized by comprising:   3. The apparatus of claim 2, wherein the mixer (30) includes a generally conical second powder impact surface (42), the second powder impact surface being the first powder impact surface. In order to form a generally conical gap (44) for passing the powder between the first powder collision surface and the surface (40), the first powder collision surface is disposed coaxially. Equipment.   3. A device according to claim 2, characterized in that the generally conical first powder impingement surface (40) has one or more recesses (4, 6).   5. The device according to claim 1, wherein the mixing member (32) is rotatably attached to a guide part (52) of the mixer, and the powder mixture collector (56) is attached to the guide part. ) And one or more passage orifices (54) in communication with the powder mixture collector.   6. The device according to claim 5, wherein at any point of each defining surface of the passage orifice (54), the defining surface forms an angle with the vertical line of less than 40 [deg.], Preferably less than 30 [deg.]. Features device.   The device according to any one of the preceding claims, wherein at any point of the defining surface (58) of the powder mixture collector (56), the defining surface is less than 40 ° with respect to a vertical line, preferably A device characterized in that it forms an angle of less than 30 °.   The device according to any one of claims 1 to 7, wherein the powder (A1, ..., ...) disposed between the distributing means and the mixer (30) below the distributing means (4, 6). An) further comprising a collector (26) of An).   9. The apparatus according to claim 8, wherein at any point of the defining surface (28) of the collector (26) of the powder (A1,..., An), the defining surface (28) An apparatus having an angle of less than, preferably less than 30 °.   10. A device according to any one of the preceding claims, characterized in that each of the distribution means (4, 6) takes the form of a powder delivery device by vibration of the powder support element (14). Do the equipment.   11. Apparatus (1) according to any one of the preceding claims, wherein the apparatus (100) for depositing a powder mixture for forming an object having a composition gradient is attached to a spatial movement means (102). And a control unit (104) capable of controlling each of the moving means (102) and the distributing means (4, 6). 12. The installation according to claim 11, wherein the control unit (104) controls each of the distribution means (4, 6) over a period T.
Change over time of the mass ratio of the powders (A1,..., An) in the powder mixture to be deposited over the period T;
A representative value of the specific gravity of the powder mixture after deposition according to the mass ratio of the powder (A1,..., An) in the mixture;
The deposition apparatus corresponding to the time elapsed between the moment when control is transmitted to the powder distribution means to obtain a powder mixture having a given mass ratio and the moment when the powder mixture is deposited; The associated waiting time (tl),
Equipment characterized by considering.   13. The installation according to claim 11 or 12, wherein the control unit (104) is employed in the powder mixture dispenser (60) over the period T to control the deposition apparatus starting means (102) over the period T. A facility characterized by taking into account changes in power position (x, y) over time.   A method for producing an object having a composition gradient with the apparatus (1) according to any one of claims 1 to 10 or the equipment (100) according to any one of claims 11 to 13, comprising: By starting the powder mixing dispenser (60) relative to the support (108), an object having a composition gradient from the formation of at least one powder mixture layer (114) deposited on the support (108). How to make.   15. The method of claim 14, wherein in order to produce the powder mixture layer (114), the powder mixture dispenser (60) is started and the surface of the support (108) on which the layer is to be deposited. And a control of at least one of the distribution means (4, 6) is changed during the sweep.

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